Abstract: An improved centrifugal pneumatic comminutor including a housing containing a fan operatively connected to a motor, the housing having an inlet opening aligned with the axis of the fan and an outlet opening on the perimeter of the housing, an input conduit mounted to the housing surrounding the inlet opening including a frustal conically shaped section adjacent the housing, and an output conduit attached to the housing surrounding the outlet opening, the material to be comminuted being introduced into the input conduit and being drawn into the frustal conically shaped section by suction of the fan. The materials are comminuted in the input conduit in a rotational impact area directly below the fan and thereafter are pulled through the fan and forced out the output conduit by the pressure of the fan. The fan includes a ring member attached to the fan which rotatably mates with a journal attached to the housing creating an air lock through the comminutor.